ScopeX Asteroids Followup Throop Oct14 - ASSA

Amateur Observations of Near-Earth
Asteroids from South Africa
Henry Throop!
Physics Department, University of Pretoria
Planetary Science Institute, Tucson, USA
1 Oct 2014
Inventory of Earth Impactors
Megatons TNT
Total
Detected
South African Airburst (1963)
Chelyabinsk (2013)
Small;
Protected!
by Earth’s !
Atmosphere
Tunguska (1908)
Large; Nearly
All Detected
Dangerous and
Not Yet Detected!
Impact Interval [years]
Number, N < D
Hiroshima
K-T Impactor (65 Mya)
Vredefort (2.2 Gya)
Absolute Magnitude H
Assumes albedo 0.14
Diameter [km]
NEAs only
All asteroids
Asteroid Type
# Known
Main-Belt Asteroids
500,000
Near-Earth Asteroids (NEAs)
Pass within 0.1 AU of Earth
11,000
Potentially Hazardous Asteroids (PHAs)
Cross Earth orbit and r > 100 m
1400
How to Handle the Asteroid Risk?
!
!
Asteroid Grand Challenge
NASA must “find all asteroid threats to human
populations and know what to do about them.”!
•
Detect all NEAs > 100 m!
•
Characterize them!
•
Determine a way to mitigate them!
US Congress, July 2013
11 time zones
Observatory with reported
NEA observations
There is a huge gap in global observational coverage of asteroids…
and it is centered on South Africa, which has a lot of telescopes!
How to Detect and Characterize Asteroids
MIT LINEAR
New Mexico
Catalina Sky Survey
Arizona & Australia
Pan-STARRS
Hawaii
•
1m - 2m wide-angle robotic telescopes have been very successful for detection: nearly 95% of
all suspected NEAs > 1 km have now been detected.
•
But the vast majority of the NEOs discovered in these searches are never observed again!
We know nothing about their shape, rotation rate, possible binaries, composition, size, etc.!
•
This is where amateurs with access to moderate facilities can play a key role. !
•
Measuring rotational light curves (~4-12 hours) of NEOs when near periapse!
•
Measuring positions of NEOs in the few weeks post-discovery for improved orbits.
Asteroid 3288 Selucus!
NEA, perihelion 1.1 AU, e = 0.45, H=15.3, v = 17, discovered 1982
We measure light curve
to determine rotation rate,
shape, binarity of
asteroid.
!
Vast majority of NEAs
have never been studied
post-discovery.
June 2014, SAAO 1m
Throop / Reddy / Morris
How South Africa can play a role !
in the Asteroid Grand Challenge and NEA studies
Discovering new NEAs
Requires wide-angle robotic
telescopes
Immediate followup post-discovery;
Geographic advantage of SA
orbital measurements
fills major hole.
Characterization: Shape, spin rate, Ready access to moderate
telescopes (<1m).
composition
Closing Thoughts
Impact risk is a non-negligible threat to humanity,
of great interest to NASA and other countries.
!
The majority of potentially hazardous asteroids
(PHAs) have not yet been discovered… and of
those known, the majority have never been
studied.
!
South African amateurs can make significant
contributions to important science.
!
Thank you!
[email protected]